Simultaneous ingestion of cocaine and alcohol results in cocaethylene production. Cocaethylene is a pharmacologically active homolog of cocaine, formed by tranesterification of cocaine in the presence of alcohol. Previously we reported that intranasal cocaethylene had behavioral and cardiovascular effects similar to cocaine, but cocaethylene appeared to have a longer elimination half-life. The slow clearence of cocaethylene could result in accumulation during binge cocaine-alcohol use and thereby increase the toxicity. However, the pharmacokinetic properties of cocaethylene could not be definitively characterized employing the intranasal route of administration due to issues of bio-availability. Currently, we are in the midst of conducting a placebo-controlled double-blind study, in which we are examining the pharmacokinetics and behavioral and physiological effects of intravenous cocaethylene in humans. Five drug administration sessions are being conducted in as many days. This study will include 14 men and 14 women. We expect to continue data collection for a 2 year period.